The winding of intermediately tapped coils to form electrical transformers has long been either a slow, tedious and basically manual operation or an expensive mechanized operation utilizing highly sophisticated equipment. The manual operation consisted of insertion of a ferromagnetic bobbin on a motor-driven spindle, holding the wire around the bobbin and manually winding the coil by starting rotation of the spindle, counting the approximate number of turns and stopping the rotation, cutting the wire for the primary, winding the secondary by starting rotation of the spindle, counting the approximate number of turns and stopping the rotation, cutting the wire for the secondary, twisting the center tap wires together, applying solvent to secure the wires, allowing drying time for the solvent, and removing the finished coil from the spindle. The manual operation has been time consuming and inexact in the number of turns wound. One operator typically could not wind more than approximately 150 coils per day. The present invention speeds up the process with mechanization utilizing a simple device. One operator using the invention may now typically wind approximately 1,000 coils per day.
Other automatic coil winders have utilized winding means consisting of the stationary core and a rotatable winding head and have utilized a step-by-step rotatable turret mechanism and have utilized automatic coil turn holding means. Winding means utilizing the rotating winding head around a stationary core have been well known as is illustrated in U.S. Pat. No. 1,579,274 which issued on Aug. 29, 1924, and in U.S. Pat. No. 3,865,152 which issued on Feb. 11, 1975, and also U.S. Pat. No. 3,724,515 which issued on Apr. 3, 1973. The use of a step-by-step rotatable turret in conjunction with the stationary bobbin winding means is also well known as illustrated by U.S. Pat. No. 3,865,152 and U.S. Pat. No. 2,782,809 which issued on Feb. 26, 1957. Thus the method of winding coils on stationary bobbins utilizing a rotatable turret mechanism with the winding wire interconnecting adjacent bobbins has been well known for some time. Various methods of holding the coil turns together after the winding wire connecting adjacent coils has been severed have also been shown as is illustrated by U.S. Pat. No. 3,865,152 which issued on Feb. 11, 1975. However, none of these apparatus have utilized an automatic intermediate tap hook mechanism for pulling an intermediate center tap on the coil nor have they utilized the automatic turn securing mechanism consisting of adhesive coated wire in conjunction with the application of a solvent and means for drying that solvent.
The present invention provides a relatively simple, inexpensive, semi-automatic machine facilitating the manufacture of intermediately tapped electrical transformers in which ferromagnetic bobbin-type cores are wound with wire. In carrying out this invention, the only manual operation is the loading of empty bobbins into spring loaded collets affixed to a rotatable turret wheel. The turret then advances the collet to a winding station. A motorized winding head, utilizing a wire bail being fed with adhesive coated magnet wire, is revolved until a counting mechanism has exactly counted the proper number of turns in the primary which had been previously set. A movable hook mechanism then catches the wire. The winding head continues to revolve while the hook mechanism is retracted and then is rotated at a relatively high speed twisting the wire until it breaks in the hook mechanism, thereby creating a finished tap. The said winding head continues to revolve until another counting mechanism has exactly counted the proper number of turns in the secondary which had been previously set and which may be different from the first count. The motorized winding head is then dynamically braked to a stop. The turret then advances, passing the wound coil through a solvent activating the adhesive coating on the wire and further advancing the wound coil through a flow of air, thereby expediting the drying of the solvent and adhesive and securing the wires. The turret then advances the wound coil past a solenoid activated cutter blade which, at the proper time, severs the wire, thereby separating the wound coil from the feed wire. The turret then advances the wound coil to a removal station where a mechanical cam releases the spring loaded collet and an electromagnet attracts the wound coil and extracts it from the collet and allows the wound coil to drop into a holding bin when the electromagnet is deactivated. The turret again advances, returning the collet to the loading station where the process then starts anew. The turret includes a plurality of such collets allowing a plurality of bobbins to be processed simultaneously, each at a different step of manufacture.